Archmage Antonidas of the Kirin Tor apparently came into the possession of an artifact known as the Book of Medivh sometime before the Third War. It was stolen from Dalaran by Arthas and Kel'Thuzad during that war and used to summon Archimonde, thus beginning the Reign of Chaos. Archimonde referred to it as "the last surviving spellbook of Medivh, the Last Guardian." Kel'Thuzad was amazed at the amount of information about demons contained in the book.

There is some debate among the fan community as to whether the references to the Book of Medivh in Warcraft II: Beyond the Dark Portal and Warcraft III refer to the same book, or to different books. Archimonde referred to the copy held in Dalaran as "the only remaining spellbook of Medivh, the Last Guardian." This would seem to imply there had been others at one time. It's also possible that Khadgar's book was entitled The Book of Medivh, whereas the one acquired by Kel'Thuzad was simply a working spellbook.

In Karazhan the Shade of Nielas Aran, the involuntary father of Medivh, has Medivh's Journal, which could also be considered a "Book of Medivh". Mages from the Violet Eye - a sect of the Kirin Tor sent to spy on Medivh - were looking for the book and went mad when they read it. It was revealed that Kamsis gave the book to the Shade of Aran. When the player reads the book at the Master's Terrace they can watch into the past how Medivh killed the mighty blue dragon Arcanagos, now better known as Nightbane.